Accession No
2831
Brief Description
compass azimuth ring, by H. Hughes & Son Ltd, English, 1930 (c)
Origin
England; London
Maker
H. Hughes and Son
Class
magnetism; navigation
Earliest Date
1930
Latest Date
1930
Inscription Date
Material
metal (oxidised brass, brass); glass
Dimensions
box depth 202mm; breadth 204mm; height 54mm
Special Collection
Provenance
Purchased from Christie’s, South Kensington, London, England, 29/04/1982.
Inscription
Description Notes
Oxidised brass bearing ring for marine compass. Open ring with 2 brass handles. 2 folding sights: one window fitted with dark glass reflector, the other slit with sliding cursor-like blank pinhole. Fitted box with H. Hughes & Son Ltd trade label.
References
Events
Description
Made by H. Hughes and Son, this compass azimuth ring was used for finding bearings at sea. It was used as an accessory to a marine compass.
More on the magnetic compass
The magnetic compass consists of a magnetic needle attached to a compass card, graduated into angular points, and is used for navigation. The first known dry pivoted compass is dated as early as 1269.
The compass indicates the direction of the magnetic pole but there are problems caused by the difference between magnetic and true north (true north being the useful reading). The variation between the two must be calculated in order to obtain an accurate reading. True north was sometimes simply offset from the direction of magnetic north, but this did not allow for geographical variation. For this, charts were needed. The iron used in building ships during 19th century also led to problems because the magnetism of iron affected the compasses on board.
31/08/2006
Created by: Saffron Clackson; updated by Ruth Horry on 31/08/2006
FM:44460
Images (Click to view full size):
